On Wednesday 27 of May 2009 8:35:49 pm Eugene Loh wrote:
At the level of this particular e-mail thread, the issue seems to me to
be different. Results are added together in some arbitrary order and
there are variations on order of 10^-10. This is not an issue of
numerical stability, but just of bitwise floating-point reproducibility.
And, given that one could fix the order (by using explicit source
processes instead of MPI_ANY_SOURCE), one could "fix" this particular
problem in MPI.
Eugene,
I really do not understand why you insist on the order. Maybe there is
something subtle about the order that I do not understand. Anyhow, I changed
the code according to your suggestion.
The original issue, still reflected by the subject heading of this
e-mail, was that a message overran its receive buffer. That was fixed
by using tags to distinguish different kinds of messages (res, jacob,
row, and col).
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